Thatcher said she was taking her ideas from Hayek, but Hayek never endorsed her policy decisions, nor was he ever her advisor.

This aside, Hayek is describing what is, he's making a positive statement, in his opinion competition should be understood as a process of discovery. The policy consequences of this framework are far removed at this point and I bet hosts of "liberal" economists such as Delong or Krugman would agree that prices emerging from such a process are one of the main feature of free-markets.